/**
* Convenience method that returns a new Chromosome instance with its genes values (alleles)
* randomized. Note that, if possible, this method will acquire a Chromosome instance from the
* active ChromosomePool (if any) and then randomize its gene values before returning it. If a
* Chromosome cannot be acquired from the pool, then a new instance will be constructed and its
* gene values randomized before returning it.
*
* @param a_configuration the configuration to use
* @return randomly initialized Chromosome
* @throws InvalidConfigurationException if the given Configuration instance is invalid
* @throws IllegalArgumentException if the given Configuration instance is null
* @author Neil Rotstan
* @author Klaus Meffert
* @since 1.0
*/
public static IChromosome randomInitialChromosome(Configuration a_configuration)
throws InvalidConfigurationException {
// Sanity check: make sure the given configuration isn't null.
// -----------------------------------------------------------
if (a_configuration == null) {
throw new IllegalArgumentException("Configuration instance must not be null");
}
// Lock the configuration settings so that they can't be changed
// from now on.
// -------------------------------------------------------------
a_configuration.lockSettings();
// First see if we can get a Chromosome instance from the pool.
// If we can, we'll randomize its gene values (alleles) and then
// return it.
// -------------------------------------------------------------
IChromosomePool pool = a_configuration.getChromosomePool();
if (pool != null) {
IChromosome randomChromosome = pool.acquireChromosome();
if (randomChromosome != null) {
Gene[] genes = randomChromosome.getGenes();
RandomGenerator generator = a_configuration.getRandomGenerator();
for (int i = 0; i < genes.length; i++) {
genes[i].setToRandomValue(generator);
/** @todo what about Gene's energy? */
}
randomChromosome.setFitnessValueDirectly(FitnessFunction.NO_FITNESS_VALUE);
return randomChromosome;
}
}
// We weren't able to get a Chromosome from the pool, so we have to
// construct a new instance and build it from scratch.
// ------------------------------------------------------------------
IChromosome sampleChromosome = a_configuration.getSampleChromosome();
sampleChromosome.setFitnessValue(FitnessFunction.NO_FITNESS_VALUE);
Gene[] sampleGenes = sampleChromosome.getGenes();
Gene[] newGenes = new Gene[sampleGenes.length];
RandomGenerator generator = a_configuration.getRandomGenerator();
for (int i = 0; i < newGenes.length; i++) {
// We use the newGene() method on each of the genes in the
// sample Chromosome to generate our new Gene instances for
// the Chromosome we're returning. This guarantees that the
// new Genes are setup with all of the correct internal state
// for the respective gene position they're going to inhabit.
// -----------------------------------------------------------
newGenes[i] = sampleGenes[i].newGene();
// Set the gene's value (allele) to a random value.
// ------------------------------------------------
newGenes[i].setToRandomValue(generator);
/** @todo what about Gene's energy? */
}
// Finally, construct the new chromosome with the new random
// genes values and return it.
// ---------------------------------------------------------
return new Chromosome(a_configuration, newGenes);
}
